Doc: Pacemaker_Explained: Fix formatting
Log: attrd: Quote attribute names
Fix: crmd: Avoid deleting the 'shutdown' attribute

Always supply a value so that any changes can get written to the DC
rather than locally (because our peers may not know about the
cib_mixed_update flag yet).

This ensures we can always shut down.
Fix: crm_attribute: Do not swallow hostname lookup failures